server.js

const express = require("express");
const app = express();
const elements = require("./data.json").elements;
const _ = require("lodash");
const PORT = process.env.PORT || 8000;
Array.prototype.paginate = function (page = 1, limit = this.length) {
  page = Number(page);
  limit = Number(limit);
  page--;
  if (
    this.slice(page * limit, page * limit + limit).length > 0 ||
    this.length > 0
  )
    return this.slice(page * limit, page * limit + limit);
  else
    return {
      error: "not found.",
    };
};

function queryParams(params, array = elements) {
  if (params["filter"]) {
    _.forEach(params["filter"], function (key, value) {
      array = array.filter((element) => element[value] == key);
    });
  }

  if (params["sort_by"]) _.sortBy(array, [array.sort_by, "number"]);
  if (params["reverse"] == "true") _.reverse(array);
  return array.paginate(params.page, params.limit);
}
// cor policy
app.use((req, res, next) => {
  res.header({"Access-Control-Allow-Origin": "*"});
  next();
}) 
app.get("/", async (req, res) => {
  res.json(queryParams(req.query));
});

app.get("/period/:period", (req, res) => {
  res.json(
    queryParams(
      req.query,
      elements.filter((element) => element.period == req.params.period)
    )
  );
});

app.get("/random", (req, res) => {
  res.json(elements[Math.floor(Math.random() * elements.length - 1)]);
});

app.get("/phase/:phase", (req, res) => {
  res.json(
    queryParams(
      req.query,
      elements.filter((element) => element.phase == req.params.phase)
    )
  );
});

app.get("/name/:name", (req, res) => {
  res.json(
    elements.filter((element) => element.name == req.params.name).paginate(1, 1)
  );
});

app.get("/number/:number", (req, res) => {
  res.json(
    elements
      .filter((element) => element.number == req.params.number)
      .paginate(1, 1)
  );
});

app.get("/symbol/:symbol", (req, res) => {
  res.json(
    elements
      .filter((element) => element.symbol == req.params.symbol)
      .paginate(1, 1)
  );
});

app.get("/category/:name", (req, res) => {
  res.json(
    elements
      .filter((element) => element.category == req.params.name)
      .paginate(1, 1)
  );
});

app.get("/spectral/:element", (req, res) => {
  if (
    req.params.element.length <= 2 &&
    elements.find((element) => element.symbol == req.params.element)
      .spectral_img != null
  ) {
    res.redirect(
      elements.find((element) => element.symbol == req.params.element)
        .spectral_img
    );
  } else if (
    req.params.element.length > 3 &&
    elements.find((element) => element.name == req.params.element)
      .spectral_img != null
  ) {
    res.redirect(
      elements.find((element) => element.name == req.params.element)
        .spectral_img
    );
  } else {
    res.json({
      error: "not found",
    });
  }
});

app.listen(PORT, async () => {
  console.log("App listening at localhost:8000");
});